Automatic time switch for electric applications and notably for signaling circuits



July 18, 1950 .1. HUSSON 5 AUTOMATIC TIME SWITCH FOR ELECTRIC APPLICATIONS AND NOTABLY FOR SIGNALING CIRCUITS Filed Dec. 15, 1948 Zn van 240 Jean 1%(550 0 Atzarngy Patented July 18, 1950 AUTOMATIC TIME SWITCH FOR ELECTRIC APPLICATIONS AND NOTABLY FOR SIG- NALING CIRCUITS J can Husson, Courbevoie, France, assignor to Societe dite: Scintex SocIetc Anonyme, Courbcvoie, France Application December 15, 1948, Serial No. 65,381 In France January 14, 1948 3 Claims. 1

The present invention has for its object an automatic time switch for electric applications and notably for signalling circuits; said time switch operates electrically and makes it possible to maintain a mechanically controlled current impulse for a short yet variable period of time.

Said time switch is characterized in that a contact member is so arranged that in its operative position it will close two circuits of which the one comprises a bimetallic strip, a flexible strip and the working circuit while the other comprises the bimetal strip thermostat heating circuit closed by the contact member. The contact stud on the bimetallic strip is located adjacent to the flexible strip and acts as a catch to keep the contact member in its operative position.

In the operative position of the contact member current flows through the contact member and both of the said circuits until the heated bimetallic strip bends to such an extent that the contact member is released by the bimetallic strip and snaps back into inoperative position. As to the bimetallic strip, it will move slowly towards its original position, at the end of which displacement the circuit is opened.

The distance between the flexible strip and the stud on the bimetallic strip can be adjusted by means of an eccentric for the purpose of controlling the time during which current is allowed to flow through the working circuit.

An embodiment of an automatic time switch according to the invention and applicable to an electric signalling circuit on board of a vehicle will now be described more specifically, reference being had to the diagrammatic drawing appended hereto.

The contact member C mounted for rocking motion on a pivot X is permanently urged by a spring towards its inoperative position; pressed against the back end of said contact member is an insulator I carried by a flexible strip R the end R. of which extends to a point close to the terminal P of the thermostat heating circuit T.

The bimetallic strip B of the said thermostat is connected with the current supply line L and its end carries a contact stud F which acts as a catch for the nose of the contact member C in the operative position of the latter as shown in dot-and-dash lines in the drawing.

Arranged close to said stud F is a stud G on a flexible strip A connected with the working circuit M and the position of which can be adjusted e. g. with the aid of an eccentric H.

The automatic time switch operates as follows:

In the inoperative position of the contact member C as shown in full lines in the drawing no current flows; as it is rocked to operative position as shown in dot-and-dash lines, it drives away the stud F on the flexible strip B and is immediately caught thereby; at the same time the strip R is deflected into engagement with the terminal P. Current flows both through the thermostat T and, owing to the engagement of the contact member and the strip A at K into the working circuit M.

As the temperature of the bimetallic strip B rises the contact stud F comes into engagement with stud G and drives it away progressively until it releases the contact member C which snaps back into its inoperative position.

The studs F and G are in engagement with each other and current goes on flowing through the working circuit.

Due to the fact that the resistance F is no longer fed with current the bimetallic strip cools down slowly until the two strips A and B are again in their original positions, the circuit then being open.

The time during which current is fed through following the actuation of the contact member C depends on the distance between the contact studs F and G, which distance can be adjusted e. g. by acting upon the eccentric H.

The circuit which as shown is intended for D. C. can be used as well with intermittent current, which in this case is applied to the thermostat 13 while the contact spring is connected with the plus pole.

By using a reverser of known design the contact member C can be actuated always in the same direction irrespective of whether the driver turns the hand lever in the one or the other direction.

Details may be modified in such a circuit, such as the way in which current is fed to the contact member and the thermostat circuit, the adjustment of the distance between the strips, etc., without thereby departing from the scope of the invention.

It is to be remarked that the bimetallic strip is raised by the action of the heat much quicker than it cools down, so that any actuation of the hand lever in the one or the other direction before the working time is completely elapsed will result in a new impulse of current being sent through the heating resistance, so that the time switch is re-started for a new full period of operation.

What I claim is:

1. A quick-acting time delay switch comprising, in combination, a conductive bimetallic strip arranged to be connected in circuit with a source of electric current, an electrical heating element arranged to heat said bimetallic strip, a resilient switch element for connecting said heating element in circuit with a source of electric current, said switch element being normally held in noncircuit making position, a conductive lever arm pivotally mounted to engage the end of the bimetallic strip when said strip is in normal position but to be released when said strip is deflected by heat from said heating element, means urging said lever arm against the end of the bimetallic strip, said lever arm engaging the switch element to move it into circuit making contact when said lever arm is moved into engagement with the end of the bimetallic strip, said switch element being insulated from said arm, a flexible conductive strip having a portion engageable with the lever arm when said arm is in engagement with the end of the bimetallic strip, whereby a current path is formed between said bimetallic strip and the flexible conductive strip through the conductive lever arm, a contact stud on said flexible conductive strip and a contact stud on said bimetallic strip spaced from said first-named stud and engageable therewith upon thermal deflection of the bi-metallic strip.

2. A quick-acting time delay switch comprising, in combination, a conductive bimetallic strip arranged to be connected in circuit with a source of electric current, an electrical heating element encircling said bimetallic strip, a switch element connecting said heating element in circuit with said current source, said switch being normally held in non-circuit making position, a pivotally mounted conductive lever arm having an end engageable with the end of the bimetallic strip when said strip is in normal non-deflected position but releasable when said strip is deflected by heat 4 from said heating element, means urging said lever arm against the end of the bimetallic strip, said lever arm engaging the switch element to move it into circuit making contact when said lever arm is pivotally moved into engagement with the end of the bimetallic strip, said switch element being insulated from said arm, a flexible conductive strip having a portion in alignment with but spaced from the bimetallic strip and engageable with the lever arm when said arm is in engagement with the end of said bimetallic strip, whereby a current path is formed between said bimetallic strip and the flexible conductive strip through the conductive lever arm, a contact stud on said flexible conductive strip and a contact stud on said bimetallic strip spaced from said first-named stud but engageable therewith upon thermal deflection of the bimetallic strip to establish a direct current path between the flexible strip and the bimetallic strip.

3. A time switch as defined in claim 1 further comprising means for adjusting the space between said first contact stud and said second contact stud to control the time period of contact between said studs.

JEAN HUSSON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,704,459 Chance Mar. 5, 1929 1,763,006 Murphy June 10, 1930 1,846,873 Johns Feb. 23, 1932 2,259,758 Luce Oct. 21, 1941 2,269,047 Woodring Jan. 6, 1942 2,387,891 Elkin Oct. 30, 1945 

